Connection device for connecting a filtering system to an incubator

ABSTRACT

A connection device for connecting a filtering system to an incubator. The connection device includes a body member adapted to fit in the wall of an incubator and having at least two bores which provide access into the incubator. The bores are equipped with fittings which provide a port for connection of tubing to direct the flow of filtered air into and out of the incubator.

This is a division of U.S. Ser. No. 08/855,899, filed May 15, 1997 nowU.S. Pat. No. 6,013,119.

BACKGROUND OF INVENTION

1. Field of Invention

This invention relates generally to an improved filtering system andmethod. More particularly, this invention relates to an improvedfiltering system and method for incubators.

2. Background

Incubators provide an isolated and controlled environment for themaintaining of cells, tissues and various organisms in vitro duringstorage, manipulation and examination. Although it is known to filterthe gaseous environment of the incubator to remove particulatematerials, it has not bee recognized that volatile organic compounds maybe present within the incubator chamber which could have a deleteriouseffect on the samples within the chamber or on the process ormanipulation being undertaken.

These undesirable volatile compounds may arise from a variety of sourcesand in a number of different ways. Such volatile compounds may bepresent in the atmosphere of the room in which the incubator is locatedand emanate from the gasing-off of many materials such as the glue usedto set the tiles in the floor, fabrics present in the room and manyother unsuspecting sources. When the incubator is opened, suchundesirable volatile compounds will enter the incubator chamber. Thesupply of gases such as CO₂ and O₂ to the incubator environment from anexternal supply may be an unsuspected source of the undesirable volatileorganic compounds.

Additionally it has been found that the materials used in the incubatorfor holding the specimens may be a source of such compounds. Sterileplastic ware such as used for petri dishes may off-gas styrene,ethyl-benzine and benzaldehyde. The media used in the culturingtechniques such as mineral oil may also contribute to the unwantedvolatile organic components.

While conventional incubators provide for airflow and filter out solidparticulate material, none have recognized that there are sources ofobjectionable volatile organic compounds that may enter the incubator,or develop within the incubator, that should be filtered out to improvethe quality of gaseous atmosphere of the incubator.

A controlled atmosphere enclosure is disclosed in U.S. Pat. No.4,701,415. According to the disclosure of that patent there is athermally insulated inner chamber containing a controlled gas atmosphereof carbon dioxide. The atmosphere of the inner chamber is drawn out, andthe level of carbon dioxide is measure and increased if necessary. Thecarbon dioxide adjusted atmosphere is then filtered through a highefficiency particulate arresting (HEPA) filter to remove particulate andthe filtered or non-particular gas is then passed through a humidifierand returned to the inner chamber. This controlled atmosphere deviceonly utilizes a HEPA filter. There is no recognition in this disclosureof the problem of gaseous impurities and no provision for theirfiltration.

Another controlled environmental chamber apparatus is disclosed in U.S.Pat. No. 5,169,217. The apparatus disclosed in this patent includes achamber for maintaining biological material under controlled conditionsof temperature and/or humidity having a door for controlling access tothe chamber. A source of HEPA-filtered air flows downward in front ofthe door creating a curtain of air when the door is opened to preventunclean air from entering the chamber. This disclosure also fails torecognize the problem of volatile organic contaminants and thedesirability of their filtration.

U.S. Pat. No. 5,352,414 discloses an incubator unit and filter systemfor performing radioactive experiments. According to the disclosure ofthis patent, the chamber is provided with static filters and the gasexhaust line is provided with an exhaust filter. According to thepatent, the gas used in the incubator environment is flushed through thechamber and exits through the exhaust filter. After flushing, thechamber is sealed off during the experimentation period. After theexperiment, the chamber is flushed again to remove the contaminatinggases and volatiles. According to the disclosure of this patent, duringthe experiment, radioactive active gases or other contaminants will bereleased into the chamber and will tend to be picked up by the charcoalpaper sheets. This patent is especially concerned with radioactivegases. There is no recognition of the problem of undesirable volatileorganic compounds. Additionally, there is no recognition of thedesirability for recirculating the gaseous environment of incubator tofilter the volatile organic compounds from the gaseous environment.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present invention toprovide an improved filtering system and method for an incubator.

A more specific object of the present invention is to provide animproved filtering system and method for an incubator which will filtervolatile organic compounds.

Another object of the present invention is to provide an improvedfiltering system for incubators which may be retrofitted to existingincubators.

These and other objects and advantages may be achieved in accordancewith one aspect of the present invention through the provision of afilter system for an incubator for filtering the gaseous environmentwithin said incubator, said incubator having a recirculating gas pathfor recirculating a gas stream from said gaseous environment, saidfilter system comprising an inlet in said recirculating gas path forreceiving a recirculating gas stream from the gaseous environment of theincubator; an outlet in said recirculating gas path for returning therecirculating gas stream to said gaseous environment of said incubator;and a volatile organic compound-removing filter medium located betweensaid inlet and said outlet for filtering said recirculating gas stream;said volatile organic compound-removing filter medium serving to filtervolatile organic compounds from said recirculating gas stream.

In accordance with another aspect of the present invention, there isprovided a filter system for an incubator for filtering volatile organiccompounds and particulate material from the gaseous environment withinthe incubator comprising an inlet for receiving a gas stream from thegaseous environment of the incubator; an outlet for returning the gasstream to gaseous environment of the incubator; and a filter connectedbetween said inlet and said outlet for filtering said stream of gas,said filter serving to filter volatile organic compounds and particulatematerial from said gas stream.

According to another aspect of the present invention, there is provideda filter unit for use in filtering volatile organic contaminants andsolid particulate material from the gaseous environment within anincubator comprising a housing; a partition dividing said housing intofirst and second compartments; a pump located in said first compartment;a filter located in said second compartment; an electrical powerconnector extending from said pump through said housing to a pointexternal of said housing; said housing having an inlet port to providefor the inflow of a gaseous stream from the interior environment of anincubator into the filter unit and an outlet port for providing of theoutflow of filtered gas stream from the filter unit to the interior ofthe incubator; and said pump and said filter being connected betweensaid inlet port and said outlet port so that said pump causes the flowof the gaseous stream into said inlet port through said pump and filterand through said outlet port to said incubator.

According to a further aspect of the invention, there is provided aconnection device for mounting in the wall of an incubator forpermitting access from the outside of the interior of said incubator forcomponents of a filtering system for filtering volatile organiccompounds and particulate material from the gaseous environment withinthe incubator comprising a body member for mounting in the wall of saidincubator and having an outer face exposed to the outside and an innerface exposed to the inside of said incubator; a first bore extendingthrough said body between said two faces; a fitting attached to saidouter face communicating with said first bore to provide an outlet portfor a gas stream from the interior of said incubator; a second boreextending through said body between said two faces; a fitting attachedto said outer face communicating with said second bore to provide aninlet port for a filtered gas stream to the interior of said incubator;and a fitting attached to said inner face in communication with saidsecond bore to provide a port for connection of tubing to direct theflow of the filtered gas steam within the incubator.

According to yet another aspect of the present invention, there isprovided a continuous process for filtering volatile organic compoundsand particulate material from the gaseous environment of an incubatorcomprising drawing a gas stream from the gaseous environment of theincubator; reducing the amount of humidity in the drawn gas stream;passing the moisture-reduced gas stream to a filter which filteredvolatile organic compounds and solid particulate material from said gasstream; introducing the filtered gas stream back into the gaseousenvironment while continuing to draw off a gas stream; and repeatingsteps a through d to provide said continuous process.

According to still further aspect of the present invention, there isprovided a filter system for use with an incubator having a supply ofgas fed to the interior of said incubator from an external storagesource, said filter system comprising a flow path for said gas from saidsource to the interior of said incubator, and a filter connected betweensaid storage source and the interior of said incubator for filteringsaid gas, said filter serving to filter volatile organic compounds andparticulate material from said gas stream.

The present invention may be better understood by reference to thefollowing detailed description and to the accompanying drawings inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a filtering system for an incubatoraccording to the present invention with the filter unit provided outsideof the incubator;

FIG. 2 is a schematic diagram of a filtering system for an incubatoraccording to the present invention with the filter unit mounted with theincubator;

FIG. 3 is an enlarged isometric view of the filter unit;

FIG. 4 is a sectional unit of the filter unit taken along the lines 4—4of FIG. 3;

FIG. 5 is an enlarged view through a section of the wall of an incubatorshowing a connector device used when the filter unit is external of theincubator;

FIG. 6 is a partial elevational view, partially in section, taken in thedirection of the lines 6—6 of FIG. 5 and showing the outside face of theconnector device of FIG. 5.

FIG. 7 is a partial elevational view taken in the direction of the lines7—7 of FIG. 5 and showing the outside face of the connector device ofFIG. 5;

FIG. 8 is an enlarged view similar to that of FIG. 5, but showing theconnector device when the filter unit is located internally of theincubator; and

FIG. 9 is a schematic diagram of another application of the filter ofthe present invention.

DETAILED DESCRIPTION

Referring to the drawings, and particularly FIGS. 1 and 2, the filteringsystem 10 of the present invention may generally include an incubator 12having a cabinet or enclosure 14, a filter unit 16, a power connector orcord 18 attached to the filter unit 16, and a water pan or reservoir 20within the incubator cabinet 14 to which the recirculating air from thefilter unit 16 is fed. The filter unit 16 contains an electrical pump 22and a filter 24.

More specifically, the incubator 12 may be any of the variouscommercially available units of the type customarily used to isolatetest samples and cultures in a controlled environment. Such incubators12 provide a chamber with a controlled environment for maintainingcells, tissues and organisms in vitro during storage, manipulation andexamination. As shown in FIGS. 1 and 2, the incubator 10 may include thecabinet 14 defined by two opposed side walls 26, a rear wall 28, a frontwall 30 including an access door (not shown), and a top 32 and bottom34. The water pan or reservoir 20 may be provided internally of thecabinet 14 on a shelf (not shown) or bottom surface 36. The rear wall 28may be provided with an aperture 38 which, in use, may be plugged orused to provide an entrance for gases from an external source.

In the embodiment shown in FIG. 1, the filter unit 16 is located outsidethe incubator cabinet 14. The filter unit 16 has an unfiltered air inletport 40 and a filtered air outlet port 42. The unfiltered air inlet port40 is connected to a moisture collector or moisture trap 44 by anincoming air line 46. As shown most clearly in FIG. 5, the moisture trap44 may be a suitable container of non-toxic material having an open top48 in which is secured a silicone stopper 50 having an aperture 52through which the incoming air line 46 passes. An outflow air line 54from the incubator 10 also extends through an aperture 56 in the stopper50 into the moisture collector 44. As will be noted in FIG. 5, both theincoming air line 46 and the outflow air line 54 terminate short of thebottom 58 of the moisture collector 44. The outflow air line 54 isconnected through a connector device 60 in the wall of the incubator 12to the interior of the incubator cabinet 14.

A filtered air outflow line 62 is attached to the filtered air outletport 42 of the filter unit 16 and extends to the connector device 60.The connector device 60 connects the line 62 with an in-going filteredair tube 64 which extends from the connector device 60 to the waterreservoir 44.

As shown in FIGS. 1 and 3, the filter unit 16 is a self-contained,free-standing unit and comprises a housing 66 including a main body 68,a connector end 70 in which the unfiltered air inlet port 40 andfiltered air outlet port 42 are located, and an indicator end 72. Thesides of the housing 66 are generally semi-circular as shown. Thehousing 66 is divided into first and second compartments 74 and 76respectively, by an internal longitudinally extending partition 78. Adoor 80, hinged to the main body 68 at hinge point 82, is provided overthe second compartment 76 to provide access thereto. The door 80 andmain body 68 completely encircle the perimeter of the ends 70 and 72 toform an enclosed unit when the door 80 is closed. The housing 66,including the ends 70 and 72, partitions 78, body 68 and door 80 are allpreferably fabricated from stainless steel, although other materialssuch as non-toxic plastics may be used including Teflon, polypropylene,PETG, and hard silicon.

Referring particularly to FIGS. 1 and 3, the pump 22, along with itsassociated motor 83, is mounted in the first compartment 74 of thefilter unit 16. The intake port 84 of the pump 22 is connected to theunfiltered air inlet port 40 by suitable tubing 86. The discharge port88 of the pump 22 is connected to a connector 90 in the partition 78 bysuitable tubing 92. The electrical power cord 18 extends from the pumpmotor 83 through the connector end 70 of the housing 66 and terminatesexternally of the filter unit 16 in an power plug 94 for connection to asuitable power source. The power plug 94 may include a suitableconverter for converting the 120 volt AC power supply to a 12 volt DCcurrent. The power cord 18 also extends to an indicator light 95 mountedin the indicator end 72 of the housing 66. The light 95, when on,provides an indication that the filter unit 16 is connected to theexternal power source and the unit is energized.

The filter 24 is mounted in the second compartment 78 of the filter unit16 and may be in the form of a filter cartridge 96. The cartridge 96includes a generally cylindrically shaped main body casing 98 in whichthe filter medium is located. An inlet port 100 at the inlet end of thebody casing 98 has one end of an L-shaped inlet tube 102 connectedthereto. The other end of the inlet tube 102 is connected to theconnector 90. An L-shaped filtered air outlet tube 104 has one endconnected to an outlet port 107 in the outlet end of the body casing 98and has its other end connected to a connector 108 in the partition 78of the filter unit 16. The outlet side of the connector 108 is connectedto the filtered air outlet port 42 in the connector end 70 of thehousing 66 by a tube 109.

Each of the connectors 90 and 108 is a spring biased, quickconnect/disconnect, type connector which prevents flow therethrough whenthe filter cartridge 96 is not attached. The connectors 90 and 108 eachinclude a bore 110 in which a reduced end portion 112 of a respectiveL-shaped inlet tube 102 or outlet tube 104 is received. When the reducedend portion 112 of the tube 102 or 104 is inserted in bore 110, it movesan internal valve sleeve 114 in the connector 90 or 108 against a springbias to permit flow through the respective connector 90 or 108. Theinlet tube 102 and outlet tube 104 are held in place in their respectiveconnectors and 108 by a spring biased detent member (not shown). Uponrelease of the detent members, the spring bias moves each valve sleeve114 into its shut-off position and ejects the end portions 112 of thetubes 102 and 104 out of the bores 110. By using a quickconnect/disconnect coupling for attaching the filter cartridge 96 to theflow path of the recirculating air in the filter unit 16, the filtercartridge 96 may be easily replaced when necessary. In addition, theautomatic flow shut off of the connectors 90 and 108 prevents externalair from entering the system when the filter cartridge 96 is removed.

The filter cartridge 96 is shown in more detail in FIG. 4. The casing 98of the filter cartridge 96 is generally cylindrical in shape andincludes an first portion 116 which includes the inlet port 100 to whichthe inlet tube 102 is connected and a second portion 118 which includesthe outlet port 108 to which the outlet tube 104 is connected. Withinthe interior of the casing 98, the first portion 116 includes a firstvolatile organic compound-removing filter medium 120 which serves tofilter and remove the undesirable volatile organic compounds. By way ofexample, the various volatile hydrocarbons which may be filtered by thefirst filter medium include alkanes, hexanes, benzenes, propenes,ethers, xylenes, methanes and combinations thereof, and the like ingaseous or vapor form. By way of example, the first medium may beuntreated carbon, activated carbon, activated charcoal, and combinationsthereof, although other materials capable of filtering out the materialslisted may be used.

The second portion 118 of the interior of the casing includes a secondparticulate material-removing filter medium 122 in the form of a hollowcylinder co-axial with the outlet port 108 and positioned against thebottom of the casing 98. The second filter medium 122 is selected tofilter out particulate material in the gas stream passing therethrough.Preferably, this medium is a high efficiency particulate arresting(HEPA) filter media although other suitable filter media may be usedsuch as non-woven filter media. The second filter medium 122 may be inthe form of a pleated filter element having a cylindrical outerperiphery 124 and an axially extending cylindrical bore 126. Examples ofparticulate material to be filtered out include air-borne solidparticles, pollen, plastic particles and rust particles, as well asparticles from the first filter medium.

The first filter medium 120 extends downward in the casing 98 andsurrounds the cylindrical second filter medium 122. This ensures thatthe gas stream passes though both filter media. If the cylindricalsecond filter medium 122 was not surrounded by material of the firstfilter medium 120, the gas stream could pass along the inner wall of thecasing 98 and through the second medium 122 without having passedthrough the first medium 120.

The pump 22 may be any suitable commercially available unit preferablyoperated by a 12 volt DC current. The pump 22 may be any suitablecommercially available unit preferably operated by a 12 volt DC currentand having a relative low flow rate. In the case where the filter unit16 is located external of the incubator 12, the flow rate of the pumpshould be sufficiently low to ensure that excess humidity is not pulledinto the system from the moisture trap 44. High flow rates will causeexcessive condensation which will be drawn into the filter. Also, theflow rate must be low enough to ensure that the air stream has enoughresidence time in the filter to maximize the filtering of thecontaminants.

With the present arrangement, in the case of the filter unit 16 beingused outside of the incubator 12, the flow rate should be equal to orless than about 0.3 liters per minute and preferably between about 0.1and 0.3 liters per minute. In the case where the filter unit 16 islocated within the incubator 12, the flow rate of the pump 22 may behigher, up to about 3.0 liters per minute. However, if it is desiredthat the filter unit 16 have universal application, the flow rate of thepump 22 should be that for an external unit.

The connector device 60 is mounted in the aperture 38 in the wall 28 ofthe incubation cabinet 14 to provide a connection for the filter unit 16between the inside and outside of the incubator 12. The connector device60, in the embodiment where the filter unit 16 is located external ofthe incubator cabinet 14 is shown particularly in FIGS. 5-7. Theconnector device 60 includes a cylindrical body 128 having a flange 130on its inner end. The cylindrical body 128 extends through the aperture38 in the wall 78 of the incubator cabinet 14 with the flange 130positioned against the inner surface 132 of the wall 78 as shown in FIG.5. The aperture 38 may be one that is normally provided in the rear wall78 of commercially available incubators for the purpose of introducingextra gases into the interior of the incubator, but which, in manyapplications, is not used. Alternatively, another apertures may beprovided in the one of the walls of the incubator 12. A tightening nut134 is threaded onto the outer surface of the cylindrical body 128 andtightened against the outside surface 136 of the wall 78 of theincubator cabinet 14 to secure the connector device 60 within the wall78.

A first aperture or bore 138 is provided through the body 128 extendingfrom an inner face 140 to an outer face 142 of the connector 60. Theaxis of this aperture 138 may lie in a vertical plane passing though theaxis of the cylindrical body 128 and in a horizontal plane positionedabove a horizontal plane passing though the axis of the cylindrical body128.

A second aperture or bore 144 exceeds through the cylindrical body 128between the inner and outer faces 140 and 142 and is positioned suchthat its axis lies in a vertical plane which is parallel to, but offsetto one side with respect to, the vertical plane passing though the axisof the cylindrical body 128. The horizontal axis containing the plane ofthe second aperture 144 may be co-planar with the horizontal plane ofthe axis of the cylindrical body 128.

A third aperture or bore 146 extends though the cylindrical body 128 ofthe connector device 60 between the inner and outer faces 140 and 142.The axis of the third aperture 146 may be in a horizontal planepositioned below the horizontal plane containing the axis of thecylindrical body 128. The vertical plane containing the axis of thethird aperture 146 may be parallel to, but offset to the side oppositethe second aperture from, the horizontal plane containing the axis ofthe cylindrical body 128.

An externally threaded fitting 148, such as a threaded nipple, isthreaded into the outer face 142 of the body 124 coaxial with the firstaperture 138. In the case where the filter unit 16 is positionedexternal of the incubator cabinet 14, this aperture 138 may be pluggedby providing a screw cap 150 on the free end of the fitting 148.Alternatively, a plug may be provided in the end of the fitting 148.

A fitting 152, such as a push to connect tube fitting, having a threadedend portion is threaded into the second aperture 144 and extends fromthe outer face 142 of the cylindrical body 128. This fitting 152provides an inlet port 154 to which the filtered air outflow line 62from the filter unit 16 is connected.

Another fitting 156 having a threaded end portion is threaded into thethird aperture 146 and extends from the outer face 142 of thecylindrical body 128. This fitting 156 provides an outlet port 158 forthe gas stream from the interior of the incubator cabinet 14. An elbow160 may be connected to the fitting 156 which includes a horizontallyextending portion 162 extending parallel to the outer face 142 of thebody 128. The outflow air line 54 to the moisture collector 44 isconnected to the free end of the elbow 160.

On the inner face 140 of the cylindrical body 128, a fitting 164, suchas a push to connect tube fitting, having a threaded end portion isthreaded into the second aperture 144. This fitting 164 provides aoutlet port 166 for the connector device 60 to which the in-goingfiltered air tube 64 to the water reservoir 20 is connected.

Also provided on the inner face 140 of the cylindrical body 128 is anangled or L-shaped tube 168 having a threaded end which is threaded intoto the third aperture 146 in a manner such that tube 168 includes astraight portion 170 extending horizontally in a direction parallel tothe inner face 140. The tube 168 provides an inlet port 172 for the gasstream from the interior of the incubator cabinet 14 to enter the bore146 in the connector device 60 and pass out of the connector device 60though the port 158 into the outflow air line 54 to the moisture trap44.

In operation of the embodiment as shown in FIGS. 1 and 5-7, wherein thefilter unit is located outside of incubator cabinet 14, the filtersystem 10 is energized by connecting the plug 94 of the power cord 18 toa suitable external power source such as a 112 volt outlet. The pump 22then draws a gas stream from the interior of the incubator 10 into thetube 168 connected to the bore 146 in the connector device 60. The gasstream passes through the connector device 60, out of the port 158 intothe outflow air line 54 to the moisture trap 44. This trap 44 willcollect any moisture in the gas stream that may have formed due tochange in temperature and pressure of the gas stream at this point ascompared with the temperature and pressure within the incubator 12.

The gas stream exits the moisture trap 44 through the incoming air line46 and passes to the input port 40 of the filter unit 16. The gas streamenters the filter unit 16 and is drawn into the intake port 84 of thepump 22 and then discharged from the discharge port 88 into the line 92where it passes through the connector 90 in the partition 78, throughline 102, into the filter 24. The gas stream is forced though bothfilter media 120 and 122 within the filter cartridge 96 so that volatileorganic compound and particulate materials are filtered out of the gasstream.

The filtered gas stream exits the filter 24 and passes through theconnector 108 in the partition 78 in the filter unit 16, through outlettube 109 and exits the filter unit 116 through the outlet port 42. Thefiltered gas stream then passes though the filtered gas outflow line 62to the inlet port 154 of the connector device 60. The filtered gasstream exits the connector device 60 though the port 164 into theincoming filter gas tube 64 to the water reservoir 20. The filtered gasstream bubbles up through the water in the reservoir 20 which serves toadd humidity to the incoming filtered gas stream. If additional humidityis not necessary, the water reservoir 20 may be omitted. As long as thepump 22 is running, a gas stream is continuously removed from theincubator 10, filtered and returned to the incubator 10 so that thegaseous environment with the incubator is being continuously filtered.

In the embodiment shown in FIGS. 2 and 8, the filter unit 16 is mountedor contained within the incubator cabinet 14. In this case, theconnector device 60 serves to provide a passage for the electrical cord18 from the filter unit 16 located in the incubator 10 to a power supplylocated external of the incubator 10. The ports 154 and 158 of theconnector device 60 may be plugged by suitable caps 174 or other meansas they are not used in this case. The power cord 18 extends through thefirst aperture 138 in the connector device 60 and passes out through thefitting 148. A silicone stopper 176 is provided about the cord 18 and isinserted into the end of the fitting 148 as shown in FIG. 8. A screw cap178, through which the power cord 18 may extend, is attached to the endof the fitting 148 to hold the stopper 176 in place and provide a tightseal about cord 18.

The operation of the system of this embodiment is essentially the sameas the system shown in FIGS. 1 and 5-7. However, in this case, since thefilter unit 16 is within the incubator cabinet 14, there is no need forthe moisture collector 44.

With the plug 94 connected to an external power supply, and the systemenergized, the gaseous stream from the gaseous environment in theincubator 10 in drawn into the filter unit 16 though the input port 40by the pump 22. The gas stream passes from the input port 40 to theintake port 84 of the pump 22 and is discharged therefrom though thedischarge port 88 to the connector 90 in the partition 78. The gasstream passes through the connector 90 to the inlet port 100 of thefilter 24. The gas stream is forced though both the filter media 120 and122 within the filter 24 so that volatile organic compounds andparticulate materials are filtered out of the gas stream.

The filtered gas stream exits the filter 24, passes through theconnector 108 in the partition 78 in the filter unit 16, and exits thefilter unit 116 through the outlet port 42. The line 64 to the waterreservoir 20 is connected directly to the outlet port 42 of the filterunit 16 so that the gas stream, upon exiting the filter unit 16, passesto the water reservoir 20 and then into the gaseous environment of theincubator 10.

With the above arrangements, an effective filtering system is providedfor the continuous filtering of volatile organic compounds andparticulate material from the gaseous environment of an incubator.

By way of example, a prototype system for testing purposes was set upwhich included a commercial incubator and a pump, external of theincubator, and having its intake connected by tubing to the interior ofthe incubator. The discharge end of the pump was connected to the inletof a filter consisting of packed carbon granules in a glass tube. Theoutlet of the filter was connected by tubing to a pan of water withinthe incubator. The pump had a flow rate of 0.1 liters per minute.Various sources of volatile organic compounds were placed in theincubator. The air in the incubator was tested for concentrations ofvarious volatile organic compounds before and after the test unit wasrun. The following Table 1 shows the level of various volatile organiccompounds before and after filtering.

TABLE 1 Pre-filtered Post-filtered Concentration Concentration (micro-(micro- Compound grams/meter³) grams/meter³) Enflurane 200 100 Acetone39 32 C-9 Branched Alkane 100 20 Methylcyclohexane 50 20 n-Decane 85 14C-8 Branched Alkane 60 10 C-11 Branched Alkane 50 10 C-11 BranchedAlkane 50 9 Decahydro-2- 40 9 Methylnaphalene Isomer Toluene 21 4.8Nonane 34 4.4 Carbon Disulfide 4.0 4.3 Styrene 45 3.0 Chloromethane 2.72.6 Benzene 8.0 2.5 Methylene Chloride 2.4 2.4 1,1,1 - Trichloroethane1.5 1.2 Octane 8.8 1.2 Chloroform 0.85 1.2 Tetrachloroethene 1.2 0.93Carbon Tetrachloride 1.0 0.84 n-Hexane 3.1 0.83 Trichlorotrifluoroehtane1.2 0.81 tert-Butyl Methyl Ether 4.3 0.72 1,2,4 - Trimethylbenzene 2.40.70

As shown by the table, the using a filter system as contemplated by thisinvention significantly reduced the level of volatile organic compoundsin the gaseous environment.

Referring to FIG. 9, another embodiment of the present invention isshown in which the interior of the incubator 12 is provided with a gasfrom an external storage source. The source of gas may be a suitabletank or canister 190 containing the desired gas under pressure andlocated external of the incubator 12. Typically, such tanks 190 may belocated a distance away from the incubator 12, even in another room, andare connected to the incubator by suitable connector tubing 192. As isconventional, the outlet of the tank 190 may be connected to theconnector tubing 190 through a pressure regulator 194, with a pressuregauge 196 downstream of the regulator 194. Examples of gases that may beintroduced into the incubator 12 from an external storage source includeoxygen, carbon dioxide and nitrogen. The specific gas introduced intothe incubator 12 at any given time depends upon the type of experimentor procedure being performed within the incubator 12.

In the embodiment shown in FIG. 9, the filter unit 16 is shown beingused to filter a gas stream from the gaseous environment of the interiorof the incubator 12 as described in connection with FIG. 1. Aspreviously described, a gas stream from the interior of the incubator 12is directed through the moisture trap 44 and the filter unit 16 andreturned to the interior of the incubator 12.

The tank 190 containing the gas to be introduced into the incubator 12is connected to the incubator 12 by the connector tubing 192. Theconnector tubing 192 is connected at its outlet end to the fitting 148in the outer face 140 of the connector 60 in the wall 28 of theincubator 12. As shown in FIG. 5, the fitting 148 communicates with thefirst bore 138 in the connector 60. A short tube 198 or other type offitting may be provided on the inside face 140 of the connector 60 incommunication with the first bore 138 to direct the incoming gas withinthe incubator 12.

A filter 200 is mounted in the line 192. The filter 200 is substantiallythe same as the filter 24 used in the filter unit 16. The filter 200includes the main body casing 98 as heretofore described having theinlet port 100 and the outlet port 108. The filter 200 also includes thefirst filter medium 120 which serves to filter and remove undesirablevolatile organic compounds and the second filter medium 122 whichfilters out particulate material as described above.

The inlet port 100 of the filter 200 has connected thereto a suitableconnector 202 to which the line 192 from the tank 190 is connected. Theoutlet port 108 of the filter 200 has a similar type connector 204connected thereto to which the line 192 to the connector 60 is attached.With the provision of the filter 192 of the type of the presentinvention as described, the incoming gas to the incubator 12 is filteredto filter out unwanted volatile organic compounds which may be presentin the gas within the tank and also will filter out solid particulatematerial such as solid sediment or rust that may have a accumulated inthe tank 192.

While the filter 200 is shown in FIG. 9 as being used simultaneouslywith the filter unit 16, the filter 200 may be used alone to filter theexternal gas supply even when the filter unit 16 is not used. In FIG. 9,the filter 200 is shown connected in the external connector tubing 192.Alternatively, the filter 200 may have its outlet port 108 connecteddirectly to the connector 60 by a suitable fitting, with the end of thetubing 192 connected to the inlet port 100. As additional alternatives,the filter 200 may be mounted on the outside of the incubator cabinet14, or positioned inside the cabinet 14 and connected by suitable tubingpassing though the wall of the cabinet 14 from the filter 200 to thetank 192, with the incoming gas being released from the outlet 108 ofthe filter 200 into the interior of the incubator. Although theinvention has been described above with reference to specificembodiments thereof, it is apparent that many changes modifications andvariations can be made without departing from the concept disclosedherein. Accordingly, it is intended to embrace all such changes,modifications, and variations that fall within the scope of the appendedclaims.

What is claimed is:
 1. A connection device for mounting in the wall ofan incubator for permitting access from the outside to the interior ofsaid incubator for components of a filtering system for filteringvolatile organic compounds and particulate material from the gaseousenvironment within the incubator comprising: a. a body member formounting in the wall of said incubator and having an outer face exposedto the outside and an inner face exposed to the inside of saidincubator; b. a first bore extending through said body between said twofaces; c. a fitting attached to said outer face communicating with saidfirst bore to provide an outlet port for a gas stream from the interiorof said incubator; d. a second bore extending through said body betweensaid two faces; e. a fitting attached to said outer face communicatingwith said second bore to provide an inlet port for a filtered gas streamto the interior of said incubator; and f. a fitting attached to saidinner face in communication with said second bore to provide a port forconnection of tubing to direct the flow of the filtered gas streamwithin the incubator.
 2. The connection device of claim 1 furtherincluding a third bore through said body member between the two faces, anipple mounted in the outer face in communication with said third bore,and an L-shaped connector attached to said inner face of said body incommunication with said bore.